[libc++] Fix noexcept behaviour of operator new helper functions (#74337)

This patch removes the noexcept specifier introduced in #69407 since the
Standard allows a new handler to throw an exception of type bad_alloc 
(or derived from it). With the noexcept specifier on the helper
functions, we would immediately terminate the program.

The patch also adds tests for the case that had regressed.

Co-authored-by: Alison Zhang <alisonzhang@ibm.com>

Author: azhan92

libcxx/src/new.cpp

@@ -20,7 +20,7 @@
 // in this shared library, so that they can be overridden by programs
 // that define non-weak copies of the functions.
 
-static void* operator_new_impl(std::size_t size) noexcept {
+static void* operator_new_impl(std::size_t size) {
   if (size == 0)
     size = 1;
   void* p;
@@ -87,7 +87,7 @@ _LIBCPP_WEAK void operator delete[](void* ptr, size_t) noexcept { ::operator del
 
 #  if !defined(_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION)
 
-static void* operator_new_aligned_impl(std::size_t size, std::align_val_t alignment) noexcept {
+static void* operator_new_aligned_impl(std::size_t size, std::align_val_t alignment) {
   if (size == 0)
     size = 1;
   if (static_cast<size_t>(alignment) < sizeof(void*))

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new.size.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new[](std::numeric_limits<std::size_t>::max());
+    (void)x;
+    assert(false);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new.size_align.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new[](std::numeric_limits<std::size_t>::max(), static_cast<std::align_val_t>(32));
+    (void)x;
+    assert(false);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new.size_align_nothrow.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new[](std::numeric_limits<std::size_t>::max(), static_cast<std::align_val_t>(32), std::nothrow);
+    (void)x;
+    assert(x == NULL);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new.size_nothrow.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new[](std::numeric_limits<std::size_t>::max(), std::nothrow);
+    (void)x;
+    assert(x == NULL);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.size.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new(std::numeric_limits<std::size_t>::max());
+    (void)x;
+    assert(false);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.size_align.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new(std::numeric_limits<std::size_t>::max(), static_cast<std::align_val_t>(32));
+    (void)x;
+    assert(false);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.size_align_nothrow.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new(std::numeric_limits<std::size_t>::max(), static_cast<std::align_val_t>(32), std::nothrow);
+    (void)x;
+    assert(x == NULL);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.size_nothrow.except.pass.cpp

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: sanitizer-new-delete
+
+#include <new>
+#include <cassert>
+#include <limits>
+#include <cstdlib>
+
+struct construction_key {};
+struct my_bad_alloc : std::bad_alloc {
+  my_bad_alloc(const my_bad_alloc&) : self(this) { std::abort(); }
+  my_bad_alloc(construction_key) : self(this) {}
+  const my_bad_alloc* const self;
+};
+
+int new_handler_called = 0;
+
+void my_new_handler() {
+  ++new_handler_called;
+  throw my_bad_alloc(construction_key());
+}
+
+int main(int, char**) {
+  std::set_new_handler(my_new_handler);
+  try {
+    void* x = operator new(std::numeric_limits<std::size_t>::max(), std::nothrow);
+    (void)x;
+    assert(x == NULL);
+  } catch (my_bad_alloc const& e) {
+    assert(new_handler_called == 1);
+    assert(e.self == &e);
+  } catch (...) {
+    assert(false);
+  }
+  return 0;
+}

libcxxabi/src/stdlib_new_delete.cpp

@@ -30,7 +30,7 @@
 // in this shared library, so that they can be overridden by programs
 // that define non-weak copies of the functions.
 
-static void* operator_new_impl(std::size_t size) noexcept {
+static void* operator_new_impl(std::size_t size) {
   if (size == 0)
     size = 1;
   void* p;
@@ -107,7 +107,7 @@ void operator delete[](void* ptr, size_t) noexcept { ::operator delete[](ptr); }
 
 #if !defined(_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION)
 
-static void* operator_new_aligned_impl(std::size_t size, std::align_val_t alignment) noexcept {
+static void* operator_new_aligned_impl(std::size_t size, std::align_val_t alignment) {
   if (size == 0)
     size = 1;
   if (static_cast<size_t>(alignment) < sizeof(void*))